113: Comparison of exhaled nitric oxyde (eNO) and Helium slope (SHe) for the early detection of graft dysfunction after heart-lung (HLT) and bilateral lung (BLT) transplantation

Abstract

The slope of the alveolar plateau for Helium (SHe) measured during a single-breath washout test allows early detection of bronchiolitis obliterans syndrome (BOS) stage 1 after lung transplantation. The aim of this study was to examine the relationship over time between the development of BOS stage 0-p and changes in both eNO and SHe. 59 patients (14 HLT and 45 BLT), of whom 17 developed BOS 0-p, were studied. There were 34 patients who had been transplanted before 09/2000 and were in BOS 0, and 25 patients who were transplanted after 09/2000. Standard pulmonary function tests, eNO (measured at 200ml/s following ERS guidelines), and single-breath washouts were measured on 765 occasions from 09/2000 to 12/2004 (median follow-up 1179 days); only data obtained while patients were free of acute infection and rejection were included in the analysis. The lowest values of eNO and SHe obtained in each of the 17 patients during the BOS 0 period (T1) were compared to values obtained at the end of the BOS 0 period immediately before the change to BOS 0-p (T2), and to values obtained during the BOS 0-p period (T3). Average (SD) values for eNO at T1, T2, and T3 were 4.0 (2.4), 4.5 (1.6), and 8.0 (6.0) ppb; corresponding values for SHe were 1.6 (1.0), 4.0 (3.3), and 5.9 (4.2) %/l. For eNO, the only significant difference was found between T3 and T1 (p <0.001); for SHe, both T2 and T3 were significantly greater than T1 (p <0.001). eNo increased above the 95% confidence interval computed from all values recorded in BOS 0 in 0/17 patients at T2, and 7/17 patients at T3; corresponding values for SHe were 10/17 at T2 and 13/17 at T3. The 7 patients who had an increase in eNO at T3 also had an increase in SHe. We conclude that 1) SHe has a better sensitivity than eNO for the early detection of graft dysfunction; 2) SHe and BOS stage 0-p have complementary roles as early markers of graft dysfunction, and adding eNO does not improve the detection.